/*
 * Copyright (c) 2007, 2021, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xpath.internal.functions;

import com.sun.org.apache.xalan.internal.res.XSLMessages;
import com.sun.org.apache.xml.internal.utils.XMLString;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.org.apache.xpath.internal.objects.XString;
import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;

/**
 * Execute the Substring() function.
 *
 * @xsl.usage advanced
 */
public class FuncSubstring extends Function3Args {
    static final long serialVersionUID = -5996676095024715502L;

    /**
     * Execute the function.  The function must return
     * a valid object.
     *
     * @param xctxt The current execution context.
     * @return A valid XObject.
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {

        XMLString s1 = m_arg0.execute(xctxt).xstr();
        double start = m_arg1.execute(xctxt).num();
        int lenOfS1 = s1.length();
        XMLString substr;

        if (lenOfS1 <= 0)
            return XString.EMPTYSTRING;
        else {
            int startIndex;

            if (Double.isNaN(start)) {

                // Double.MIN_VALUE doesn't work with math below
                // so just use a big number and hope I never get caught.
                start = -1000000;
                startIndex = 0;
            } else {
                start = Math.round(start);
                startIndex = (start > 0) ? (int) start - 1 : 0;
            }

            if (null != m_arg2) {
                double len = m_arg2.num(xctxt);
                int end = (int) (Math.round(len) + start) - 1;

                // Normalize end index.
                if (end < 0)
                    end = 0;
                else if (end > lenOfS1)
                    end = lenOfS1;

                if (startIndex > lenOfS1)
                    startIndex = lenOfS1;

                substr = s1.substring(startIndex, end);
            } else {
                if (startIndex > lenOfS1)
                    startIndex = lenOfS1;
                substr = s1.substring(startIndex);
            }
        }

        return (XString) substr; // cast semi-safe
    }

    /**
     * Check that the number of arguments passed to this function is correct.
     *
     * @param argNum The number of arguments that is being passed to the function.
     * @throws WrongNumberArgsException
     */
    public void checkNumberArgs(int argNum) throws WrongNumberArgsException {
        if (argNum < 2)
            reportWrongNumberArgs();
    }

    /**
     * Constructs and throws a WrongNumberArgException with the appropriate
     * message for this function object.
     *
     * @throws WrongNumberArgsException
     */
    protected void reportWrongNumberArgs() throws WrongNumberArgsException {
        throw new WrongNumberArgsException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_TWO_OR_THREE, null)); //"2 or 3");
    }
}
